International conservationists have warned of a catastrophic decline in wildlife in Mongolia.

The vast, sparsely-populated country was once a refuge for the large mammals of Central Asia.

But in a new report, the Zoological Society of London said illegal hunting and trade had forced many species to the brink of extinction.

The red deer, snow leopard, wild camel and Gobi bear are all vanishing from the steppes, the report says.

Some species have declined by as much as 92% in the last 18 years, and there are fewer than 50 bears left.

Dr Jonathan Baillie from the Zoological Society of London says the problems began after the collapse of communism.

"In the early 1990s... the social system changed rapidly. It was formerly heavily influenced by the Soviet Union, and with the collapse of the Soviet Union there was high unemployment, and also the regulatory mechanisms broke down, so wildlife trade really increased," he said.

"There's trade both to Russia and the new market of China, and so there's just amazing volumes going across the border."

Law enforcement on hunting and trading has became increasingly lax, and vehicles and guns are far more widely available.

The Zoological Society has begun working with local partners in Mongolia to try to reverse the trend.

There is at least one precedent for this - the last breed of wild horse in Mongolia was declared extinct 10 years ago, but it has since been re-introduced by conservationists.

Now there are more than 250 such animals roaming the steppes once again.